Analog systems and digital systems are commonly implemented in an integrated circuit using system on-chip (SOC) technology. Such systems commonly include an analog front end (AFE) circuit. The AFE circuit operates as an interface between an external input terminal, through which analog signals are input, and a digital signal processing unit that processes the received signals in digital format.
The AFE circuit is widely used in various devices, such as down converters for wireless digital communication devices, digital image scanners, digital cameras and voice codecs, and the like. The AFE circuit includes an analog to digital converter (ADC). The ADC converts an analog input signal into a digital signal. An amplifier used in the ADC for amplifying has gain error. This introduces spurs and results in degradation in performance of the ADC.
Also, the amplifier is one of the most power consuming device in the ADC. In high speed operation, the amplifier can also have memory which is the charge stored with respect to inputs in previous cycles. This hinders generation of an accurate digital output by the ADC.